It has long been known to add an attractive or original function to the functions of time indication in a timepiece, such as a watch or clock, by causing the appearance of the timepiece to change when the course of time according to the relative position of the indicator members.
Swiss Pat. No. 354 031, for example, describes a timepiece comprising, between the face and the glass, two transparent disks with zones having a polarizing effect. One of the disks is fixed to the glass, while the other is firmly connected to the second-hand shaft. The relative movement of the polarizing zones causes a play of light and shadow on the face.
The watch described in Swiss Pat. No. 429 599 also comprises two polarizing disks. One of them is positioned on an image carried by the face and the other is mounted on the second-hand shaft. When the second-hand shaft rotates the image appears and disappears.
In the watch according to Swiss Pat. No. 512 770 the face and a transparent disk mounted on the second-hand shaft are provided with designs of predetermined colours and patterns which cooperate with each other to produce special optical effects when the disk rotates.